diff --git a/.changeset/mighty-needles-count.md b/.changeset/mighty-needles-count.md
new file mode 100644
index 0000000000..a845151cc8
--- /dev/null
+++ b/.changeset/mighty-needles-count.md
@@ -0,0 +1,2 @@
+---
+---
diff --git a/server/public/admin-addie.html b/server/public/admin-addie.html
index 8ac3d24e60..82b38238c4 100644
--- a/server/public/admin-addie.html
+++ b/server/public/admin-addie.html
@@ -3120,6 +3120,7 @@ <h4>Pattern Identified</h4>
     let currentThreadData = null;
     let currentConversationData = null;
     let extractedLinks = [];
+    let currentUserNames = {}; // Map of Slack user IDs to display names
 
     async function viewThread(threadId) {
       try {
@@ -3127,6 +3128,7 @@ <h4>Pattern Identified</h4>
         const data = await response.json();
         currentThreadData = data;
         currentConversationData = data;
+        currentUserNames = data.user_names || {};
 
         const channelLabel = data.channel.charAt(0).toUpperCase() + data.channel.slice(1);
         document.getElementById('conversation-modal-title').textContent =
@@ -3443,6 +3445,13 @@ <h4>Pattern Identified</h4>
     }
 
     function renderMarkdown(text) {
+      // Replace Slack user mentions with display names before escaping HTML
+      // Format: <@U1234567> -> @DisplayName
+      text = text.replace(/<@(U[A-Z0-9]+)>/g, (match, userId) => {
+        const displayName = currentUserNames[userId];
+        return displayName ? `@${displayName}` : match;
+      });
+
       // Escape HTML first
       text = text.replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;');
 
diff --git a/server/src/addie/member-context.ts b/server/src/addie/member-context.ts
index b07df117e0..cb22cc6182 100644
--- a/server/src/addie/member-context.ts
+++ b/server/src/addie/member-context.ts
@@ -15,6 +15,7 @@ import { getThreadService } from './thread-service.js';
 import { workos } from '../auth/workos-client.js';
 import { logger } from '../logger.js';
 import { getPool } from '../db/client.js';
+import { resolveSlackUserDisplayName } from '../slack/client.js';
 
 const slackDb = new SlackDatabase();
 const memberDb = new MemberDatabase();
@@ -255,22 +256,23 @@ export async function getMemberContext(slackUserId: string): Promise<MemberConte
   };
 
   try {
-    // Step 1: Look up Slack user mapping
-    const slackMapping = await slackDb.getBySlackUserId(slackUserId);
+    // Step 1: Look up Slack user (checks DB first, then API with persistence)
+    const resolved = await resolveSlackUserDisplayName(slackUserId);
 
-    if (!slackMapping) {
-      logger.debug({ slackUserId }, 'Addie: Slack user not found in mappings');
+    if (!resolved) {
+      logger.debug({ slackUserId }, 'Addie: Could not resolve Slack user');
       return context;
     }
 
     context.slack_user = {
-      slack_user_id: slackMapping.slack_user_id,
-      display_name: slackMapping.slack_display_name || slackMapping.slack_real_name,
-      email: slackMapping.slack_email,
+      slack_user_id: resolved.slack_user_id,
+      display_name: resolved.display_name,
+      email: resolved.email,
     };
 
-    // Step 2: Check if mapped to WorkOS user
-    if (!slackMapping.workos_user_id) {
+    // Step 2: Check if user is mapped to WorkOS (need full record for workos_user_id)
+    const slackMapping = await slackDb.getBySlackUserId(slackUserId);
+    if (!slackMapping || !slackMapping.workos_user_id) {
       logger.debug({ slackUserId }, 'Addie: Slack user not mapped to WorkOS');
       return context;
     }
diff --git a/server/src/routes/addie-admin.ts b/server/src/routes/addie-admin.ts
index faa56795a7..cd5ef52a31 100644
--- a/server/src/routes/addie-admin.ts
+++ b/server/src/routes/addie-admin.ts
@@ -22,6 +22,10 @@ import { getAddieBoltApp } from "../addie/bolt-app.js";
 import { AddieRouter, type RoutingContext } from "../addie/router.js";
 import { sanitizeInput } from "../addie/security.js";
 import { runSlackHistoryBackfill } from "../addie/jobs/slack-history-backfill.js";
+import {
+  resolveSlackUserDisplayName,
+  resolveSlackUserDisplayNames,
+} from "../slack/client.js";
 
 const logger = createLogger("addie-admin-routes");
 const addieDb = new AddieDatabase();
@@ -445,7 +449,39 @@ export function createAddieAdminRouter(): { pageRouter: Router; apiRouter: Route
         return res.status(404).json({ error: "Thread not found" });
       }
 
-      res.json(thread);
+      // Collect all Slack user IDs that need resolution
+      const userIdsToResolve: string[] = [];
+      const slackMentionRegex = /<@(U[A-Z0-9]+)>/g;
+
+      // Add thread owner
+      if (thread.user_id && thread.channel === "slack") {
+        userIdsToResolve.push(thread.user_id);
+      }
+
+      // Extract from all message content
+      for (const msg of thread.messages) {
+        if (msg.content) {
+          let match;
+          while ((match = slackMentionRegex.exec(msg.content)) !== null) {
+            userIdsToResolve.push(match[1]);
+          }
+        }
+      }
+
+      // Resolve all user names with concurrency limiting
+      const userNames = await resolveSlackUserDisplayNames(userIdsToResolve);
+
+      // Get display name for thread owner (may already be resolved above)
+      let displayName: string | null = thread.user_display_name;
+      if (!displayName && thread.user_id && thread.channel === "slack") {
+        displayName = userNames[thread.user_id] ?? null;
+      }
+
+      res.json({
+        ...thread,
+        user_display_name: displayName || thread.user_display_name,
+        user_names: userNames,
+      });
     } catch (error) {
       logger.error({ err: error }, "Error fetching thread");
       res.status(500).json({
diff --git a/server/src/slack/client.ts b/server/src/slack/client.ts
index e4faa766cb..8494c497dd 100644
--- a/server/src/slack/client.ts
+++ b/server/src/slack/client.ts
@@ -6,6 +6,7 @@
  */
 
 import { logger } from '../logger.js';
+import { SlackDatabase } from '../db/slack-db.js';
 import type {
   SlackUser,
   SlackChannel,
@@ -13,6 +14,15 @@ import type {
   SlackBlockMessage,
 } from './types.js';
 
+// Lazy-initialized database instance for user persistence
+let slackDb: SlackDatabase | null = null;
+function getSlackDb(): SlackDatabase {
+  if (!slackDb) {
+    slackDb = new SlackDatabase();
+  }
+  return slackDb;
+}
+
 // Use ADDIE_BOT_TOKEN as the primary token (fall back to SLACK_BOT_TOKEN for migration)
 const SLACK_BOT_TOKEN = process.env.ADDIE_BOT_TOKEN || process.env.SLACK_BOT_TOKEN;
 const SLACK_API_BASE = 'https://slack.com/api';
@@ -208,6 +218,101 @@ export async function getSlackUser(userId: string): Promise<SlackUser | null> {
   }
 }
 
+/**
+ * Result from resolving a Slack user's display name
+ */
+export interface ResolvedSlackUser {
+  slack_user_id: string;
+  display_name: string | null;
+  email: string | null;
+}
+
+/**
+ * Resolve a Slack user ID to display name, checking database first then API.
+ * Persists to database for future lookups.
+ */
+export async function resolveSlackUserDisplayName(
+  slackUserId: string
+): Promise<ResolvedSlackUser | null> {
+  const db = getSlackDb();
+
+  // Check database first
+  const existing = await db.getBySlackUserId(slackUserId);
+  if (existing) {
+    return {
+      slack_user_id: existing.slack_user_id,
+      display_name: existing.slack_display_name || existing.slack_real_name,
+      email: existing.slack_email,
+    };
+  }
+
+  // Fetch from Slack API and persist
+  try {
+    const slackUser = await getSlackUser(slackUserId);
+    if (!slackUser) {
+      return null;
+    }
+
+    const displayName = slackUser.profile?.display_name ||
+                       slackUser.profile?.real_name ||
+                       slackUser.real_name ||
+                       null;
+    const email = slackUser.profile?.email || null;
+
+    // Persist for future requests
+    await db.upsertSlackUser({
+      slack_user_id: slackUserId,
+      slack_email: email,
+      slack_display_name: slackUser.profile?.display_name || null,
+      slack_real_name: slackUser.profile?.real_name || slackUser.real_name || null,
+      slack_is_bot: slackUser.is_bot,
+      slack_is_deleted: slackUser.deleted,
+    });
+
+    logger.debug({ slackUserId, displayName }, 'Resolved and persisted Slack user from API');
+
+    return {
+      slack_user_id: slackUserId,
+      display_name: displayName,
+      email: email,
+    };
+  } catch (error) {
+    logger.debug({ slackUserId, error }, 'Failed to resolve Slack user');
+    return null;
+  }
+}
+
+/**
+ * Resolve multiple Slack user IDs to display names with concurrency limiting.
+ * Returns a map of user ID -> display name.
+ */
+export async function resolveSlackUserDisplayNames(
+  slackUserIds: string[],
+  concurrency = 5
+): Promise<Record<string, string>> {
+  const results: Record<string, string> = {};
+  const uniqueIds = [...new Set(slackUserIds)];
+
+  // Process in batches to avoid rate limiting
+  for (let i = 0; i < uniqueIds.length; i += concurrency) {
+    const batch = uniqueIds.slice(i, i + concurrency);
+    const batchResults = await Promise.all(
+      batch.map(async (userId) => {
+        const resolved = await resolveSlackUserDisplayName(userId);
+        return { userId, displayName: resolved?.display_name };
+      })
+    );
+
+    for (const { userId, displayName } of batchResults) {
+      if (displayName) {
+        results[userId] = displayName;
+      }
+    }
+  }
+
+  return results;
+}
+
 /**
  * Look up a user by email address
  */